Electrical detecting circuit and device for testing the same



H C. GRANT, JR ELECTRICAL DETEC Aug. 31, 1948. El AL 2,448,026

'rme CIRCUIT AND DEVICE FOR 'rms'rme THE SAME 2 Sheets-Sheet 1 Filed April 10, 1943 wig/enters law 6' me: 1:

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ELECTRICAL DETECTING CIRCUIT AND DEVICE FOR TESTING THE SAME Filed April 10, 1945 2 Sheets-Sheet 2 Gttormg wxmwwwgni &

' IIIIIIII/III!lI/lI/IIII/II/IIII/IIIIII/I- e Patented Aug. 31, 1948 ELECTRICAL DETECTING CIRCUIT AND DEVICE FOR TESTING THE SAME Harry C(Grant, Jr., New York, and Arthur W.

Uhl, Inwood, N. Y., assignors to Specialties Development Corporation, Bloomfield, N. J a corporation of New Jersey Application April 10, 1943, Serial No. 482,572

8 Claims. (Cl. 177-311) may be installed in airplanes or other craft or vehicles and may be employed to effect operation of an alarm or signal indicating that a state of emergency exists. If desired the circuit may be utilized, in addition, to effect operation of systems for combating th emergency. For example, in response to heat or flame, a fire extinguishing system may be operated; and in response to submersion in salt water, suitable airplane flotation gear may be operated.

The present invention aims to provide a detecting circuit of the foregoing character which may be tested to determine if any of the circuit closing elements are in circuit closing position or are short circuited. The invention further aims to provide a device for testing the circuit having indicating means which in turn may be tested.

An object of the invention is to provide a simple detecting circuit which may be readily tested.

Another object is to provide a detecting circuit including a testing device which is readily connected in the circuit.

Another object is to provide a simple, compact device for testing the circuit, which may be installed on the dash board or control panel of a vehicle.

Another object is to provide a circuit testing device having indicating means responsive to conditions of the circuit which are so wired in the circuit that they may be tested to determine whether or not they are in operating condition.

A further object consists in the combination of elements and arrangement of parts wherebythe foregoing objects may be accomplished.

Other and further objects of the invention will b obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of-the invention in practice.

A preferred embodiment of th invention has been chosen for purposes of illustration and de- 2 scription and is shown in the accompanying drawings, forming a part of the specification, wherein:

Figure 1 is a wiring diagram of an electrical circuit, illustrating an embodiment of the invention.

Figure 2 is a front elevational view of a circuit testing device in accordance with the invention.

Figure 3 is a sectional view taken substantially along the line 33 on Figure 2.

Figure 4 is a rear view of the device shown in Figures 2 and 3, a casing thereof being indicated in section to show parts in elevation.

Figure 5 is a sectional view of a circuit testing device illustrating a modified embodiment of the invention, together with a wiring diagram for the device. 1

Referring to th drawings, and more particularly to Figure 1, there is shown a circuit for detecting flame or predetermined high'temperatures. A series of detecting devices iii are connected in the circuit, as about to be described, each of which-comprises a pair of circuit closing elements ii and H' each adapted to bridge a pair of contacts or terminals l2 and I4, and i2 and M, respectively. The terminals l2 of the elements II are connected to one side or line l5 of the circuit, while the terminals l2 of the elements I l' are connected to the other side or line IS. The terminals 14 of th elements II and the terminals M of the elements II are connected to common terminal means or a line I! for the purpose to be described hereinafter.

The circuit closing elements I I and l I normally are held in open circuit position but are permitted to bridge their respective contacts in response to flame or high temperature. By providing a pair of circuit closing elements for each detecting device I0, arranged in series, both elements must bridge their contacts or terminals to close the circuit. This prevents premature operation of the detecting circuit in the event one of the circuit closing elements is permitted to bridge its contacts due to some mechanical defect.

Suitable thermo-responsive detecting devices adapted to be used in the circuit disclosed herein are illustrated in application Serial Number 343,271, filed Jung 29, 1940, entitled Thermoresponsive device, now Patent Number 2,318,607, granted May 11, 1943.

A device 20 for testing the circuit, will first be described with reference to its electrical connect-ions and its relation to the detecting circuit as shown in Figure 1. Generally, the device 20 comprises a pair of indicating devices, and a pair of switches so connected to each other and in the circuit that it is possible to determine whether or not the indicating devices are in working order, whether or not an element II or II is in its circuit closing position, and when one of the detecting devices has been operated due to name or high temperature causing its elements H and II to close the circuit by connecting lines l5 and I6.

The indicating devices may be lamps 2| and 22 connected in parallel with respect to each other and in series with respect to the circuit between terminals 24 and 25. The switches 26 and 21 may be of the normally open circuit push button type,

and are connected in series with respect to each other between terminals 26 and 29. The lamps and switches are operatively connected in the circuit by connecting one side of the detecting circuit or line Hi to the terminal 29, connecting the other side of the detecting circuit or line l6 to the terminal 25, and connecting the common line H of the detecting circuit between the switches 26 and 21 at '39. In order to provide a source of electrical energy and to complete the circuit, one pole of a battery 3| is connected to the terminal 24 and the other pole of the battery is connected to the terminal 29. If desired one pole of the battery may be grounded and terminal 24 or terminal 29 may be grounded.

In operating the testing device to determine whether or not the lamps are in working order, both switches 26 and 21 are closed simultaneously. Current will flow from one pole of the battery to the terminal 24, will divide and pass through the lamps to the terminal 25, will flow through the closed switches 26 and 21 to the terminal 29, and will return to the other pole of the battery. If the lamps are in working order they will light. A defective lamp will not light and hence can be detected and replaced.

In order to detect that one of the elements II is in circuit closing position, the switch 21 is closed. Current will flow from one pole of the battery to the terminal 24, through the lamps to the terminal 25, through the switch 21 to the common line l1 and across the-contacts l2 and H which are closed by their element through the line l5 to the terminal 29, and to the other pole of the battery. Both lamps will light giving an indication that one of the elements I I is in circuit closing position.

"In order to detect that one of the elements H is in circuit closing position, the switch 26 is automatically indicating that the detecting system has been operated.

It will be understood that operation of a fire extinguishing system or other emergency system could be eifected automatically by the detecting circuit, or that upon automatic lighting of the lamps such a system could be operated manually.

In Figures 2, '3 and 4 a practical embodiment of a testing device 29 is illustrated. The device is in the form of a compact unit comprising a supporting member, such as a mounting plate 36; a unit 36 secured to the'mounting plate having a pair of sockets 31 and 39 for the lamps 2| and 22, respectively, which extend outwardly through suitable openings in the mounting plate (Figure 3); and a unit 39 secured to the mounting plate and housing the switches 26 and 21 which are operated by push buttons 49 and 4|, respectively, urged outwardly through suitable apertures in the mounting plate by resilient means 42 (Figure 3).

The switches, sockets and lamps are electrically connected by conductors in the manner illustrated in the wiring diagram, Figure 1, and more particularly as shown in Figure 4. For example a conductor 45 connects the sockets 31 and 36, which are in electrical contact with one side of the lamps 2| and 22, respectively, to the terminal 24, and conductors 46 and 41 connect the other side of the lamps 2| and 22, respectively, to the terminal 25. The switches 26 and 21, respective- 1 close the circuit between the terminals 29 and 26 and a conductor 49 having the line l1 connected thereto at 39.

closed. Current will fiow from one pole of the battery to the terminal 24, through the lamps to the terminal 25, through the line l6 and across the contacts l2 and I4 which are closed by their element through the common line H to 39, through the switch 26 to terminal 29, and to the other pole of the battery. Both lamps will light giving an indication that one of the elements H is in circuit closing position.

In the event that an element II or I is found to be in circuit closing position it is placed in open circuit position or the faulty detecting device is replaced by one having its elements in proper open circuit position.

The foregoing tests usuallyare made preparatoryto the flight of a plane or before sending a land vehicle, such as an armored tank, into action.

Inaddition to serving as a circuit testing device, the device 29 is adapted to indicate when a pair of elements II and H engage their respective contacts l2 and I4, and I2 and I4 and thereby close the detecting circuit. Should this occur,

A box or casing 69, a section of which is removed in Fig. 4, is secured to the back of the mounting plate 36 for housing the socket and switch units 36 and 39. If desired, the box 69 may be secured to the structure of the craft or vehicle on which the testing device 29 is used.

A suitable panel 6|, preferably, is superimposed upon the front of the mounting plate and is detachably secured thereto. The panel is provided with apertures through which the push buttons 49 and 4| extend, and is provided with a protective casing portion 62 for housing the exposed ends of the lamps 2| and 22. By being detachably secured, the panel 6| may be readily removed to facilitate replacement of. the lamps.

The panel 6|, preferably, is formed of a translucent plastic molding composition of the cellulose acetate type or the like, so that the lamps, when illuminated, can be readily seen through the casing portion 62. If desired, the walls of the casing portion may be thinner than the other portions of the panel to render it more translucent. The panel can be readily molded and may be provided with suitable legend or indicia.

In Figure 5 a modified testing device 29' is illustrated which comprises, generally, a mounting plate 36', a panel 6| on the front of the mounting plate, and sleeves 64 and 66 secured to the back of the mounting plate for facilitating compact assembly of push buttons, lamps. lamp sockets and switch contacts, as about to be described.

The sleeves 64 and 56 have assembled therewith lamp sockets 31 and 36' slidably mounted member 52' provide a switch 21'.

, in the sleeves at the ends secured'to the mounting plate 35'. Lamps 2| and 22 are mounted in the sockets and have one of their contacts 56 extending through the sockets. Suitable hollow cap-like push buttons 40' and 4| are secured to sockets 31' and 38', respectively, and extend outwardly from the front of the device through apertures provided in the mounting plate 35' and the panel 5|. The push buttons house the lamps and are formed of translucent material to permit the lamps to be seen therethroughwhen they are illuminated.

The contacts 56 of the lamps are engaged by one end of contact pins 51 and 51 slidably' mounted in the sleeves. Preferably, one end of each of the pins is supported by a disc 58 and the other end of each of the pins is slidably supported in a bushing 59 secured in the corresponding sleeve 54 or 55. A spring 5|) is mounted on each of the pins, intermediate the disc 58 and the bushing 59. These springs are adapted to urge the pinsinto' contact with the contact 56 of the lamp. The ends of the sleeves opposite the ends secured to the mounting plate have bushings 5| secured therein supporting contact members 62 and 62, respectively. The foregoing described elements are assembled in the sleeve 55, so that the pin 51 is adapted to engage thecontact member 62 when the push button 4| is moved inwardly toward the sleeve 55, the pin 51 being moved toward the contact member by the contact 56- of the lamp- 22 movable with the push button 4|.

In order to provide an electrical, circuit, aboutto be described, the elements are assembled in the sleeve 54 so that the pin 51 does not'contact thecontact member. 62 to close an electrical circuit. Preferably the pin '51- moves or carriesv 6 l5 0! the detecting circuit is connected to the terminal 29' which is connected to the pin 66 and to the other side of the battery 3|.

The operation of the testing device 20 is substantially the same as the operation of the device 20 described herein. The lamps 2 and 22' may be tested by pushing the buttons 40 and Al inwardly at the same time. This causes the pins 65 and 51' to engage their respective contact members 62 and 52' whereby the lamp circuit is closed, starting from one side of the batte 3| to the terminal 24', through the lamps to theircontacts 56 which engage pins 51 and 51',

through switches 21 and 26' to the pin to terminal 29 and to the other side of the battery.

If the lamps are in working order they will both be illuminated. 1 k

In order to determine whether or not a circuit is closed between lines i5 and H, the button 4| is pushed inwardly. In the event the circuit is closed between lines l5 and I1, a circuit will be completed through the lamps, starting from one side of the battery 3| to the terminal 24;

through the lamps to the terminal 25', through switch 21", which is closed, to the line l1, and acrossvto the line l5, connected to the other side of the battery by way of terminal 29.

In order to determine whether or not ablr- I cuit is closed between lines l5 and H", the butanother member insulated from the pin which engages the contact member 62 to close a circuit. This may be, accomplished. by slidably v mounting a second pin 65 in the sleeve54 having other end slidably supported by a bushing '61 secured in the sleeve-'54. The pin 65 is normally heldout of engagement with the contact memone end supported by a disc'66 and having' itsacross to line l5 to terminal. 25, and backitober 52 by a spring 69 mounted on the pin be:

tween the disc 68 and the bushing 61. The.

spring 69 urges the pin toward thepin 51,

but a disc 10 of insulating material prevents electrical contact between the pins 51 and 65. When the push button "40' is moved inwardly toward the sleeve 54, the lamp contact 56 moves the pin 51 which in turnmoves the pin 55.

The device 20' is adapted to be electrically connected in a circuit corresponding to the circuit illustrated in Figure 1 and described in connection therewith. To accomplish this, the lamps 2| and 22 are connected in parallel between terminals 24and 25' by connecting togetherone ton 40 is pushed inwardly. In the event the circuit is closed between lines l6 and H; a circuit will be completed through the lamps, starting from one side of the battery 3| to the terminal 24; through the lamps to the terminal 25' and line'l8, across to linel1, through -switch 26';=which is -closed, .to terminal 29' and .back toqthewother side of thebattery.

In the event electrical contact is established between lines 15 and IS, a circuit will be completed through the lamps, starting from one side of the battery 3| to the terminal 24, through r the lampseto the terminal 25 and'to line -|I",

the other .side of the battery.

In' view of the foregoing description itwillbe seen that the present invention provides ,a simple.

detecting circuit and a testing device for the circuit, The testing device is compact in arrangement and sturdy in construction and is readily used for testing a number of conditions which may exist in thecircuit.

the occurrence of an emergency sets off the de- As various changes maybe made in the form, 1

construction and arrangement of the parts herein, without departing from the. spi n pe of contact of each lamp and connecting together 'the' pins 51 and 51 which are inele'ctrical connec-' tion with the other contact 56 ofthe respective lamps. The terminal 24' has one-side of a battery 3| connected thereto and the terminal 25,

(in connection with the'pins 51 and 51') has a;

line l6 of the detecting circuit (not shown) conl nected thereto. I

The pin 55 and the contact member 62 provide a switch 26, and the pin 51"and the contact 26 and 21' are connected in series by connecting the contact members 62 and 62"." The common line l1 of the detecting circuit is connected between the switches 26' and 21' at 30'. The line The switches theinvent'ion and without sacrificing-any of its advantages, it is tobe understood that all matter herein is i170 be interpreted as illustrative and not in any limiting sense.

It is also, to be understood that the following claims are intended to cover all the generic and specific features of the invention herein described, and all statements of. the scope of the inf vention which as a,matter of language, might be'said-to iall therebetween.

weic aimr 1. In-combination, electric circuit means for 7 detecting external physical conditionsincluding switch means responsive to such condition for controlling said circuit means, and means for testing saidcircuit means comprisinga series cir- In addition, the test- .ing device serves as a visual alarm inthe event cuit including said switch means, a second switch means, a source of electromotive force, and a plurality of electro responsive indicating devices connected in parallel relation to each other in said series circuit.

2. In combination, electric circuit means for detecting external physical conditions including a pair of electrically connected switch means responsive to such conditions for controlling said circuit means, means for testing said circuit means comprising a second pair of electrically connected switch means, a common conductor connected from a point between the switch means of said first pair to a point between the switch means of said second pair, a source of electromotive force, electro responsive indicating means. and conducting means whereby, when a selected one of either of said second switch means is closed, a series circuit is established therefrom through said common conductor, one of said first switch means, said source, said indicating means and back to the selected switch means.

3. In combination, electric circuit means for detecting external physical conditions including a pair of electrically connected switch means responsive to such conditions for controlling said circuit means, means for testing said circuit means comprising a second pair of electrically connected switch means, a common conductor connected from a point between the switch means of said first pair to a point between the switch means of said second pair, a source of electromotive force, electro responsive indicating means, conducting means whereby, when a selected one of either of said second switch means is closed, a series circuit is established therefrom through said common conductor, one of said first switch means, said source, said indicating means and back to the selected switch means, and a test circuit for the indicating means, closure of both said second switch means operating to close the last named circuit and to energize said indicating means.

4. In combination, electric circuit means for detecting external physical conditions including a pair of electrically connected switch means responsive to such conditions for controlling said circuit means, means for testing said circuit means comprising a second pair of electrically connected switch means, a common conductor connected from a point between the switch means of said first pair. to a point between the switch means of said second pair, a source of electromotive force, a plurality of electro responsive indicating means connected in parallel circuit relation to each other, and conducting means whereby, when a selected one of either of said second switch means is closed, a series circuit is established therefrom through said common conductor, one of said first switch means, said source, said parallel circuit, and back to the selected switch means, closure of both switches of said second pair of electrically connected switch means operating to close the said parallel circuit to energize said indicating means.

5. In combination, electric circuit means for detecting external physical conditions including a plurality of pairs of switch means responsive to such conditions for controlling said circuit means the switch means of each pair of which are connected in series relation to each other and the respective pairs of which are connected in parallel circuit relation to each other, means for testing said circuit means comprising a pair of electricaily connnected test switch means, common conductor means connecting points between the switch means of each of said plurality of pairs to each other and to a point between the switch means of said testing pair, a source of electromotive force, electro responsive indicating means, and conducting means whereby, when a selected one of either of said test switch means is closed. a series circuit is established therefrom through said common conductor means, said parallel circuit, said source, said indicating means and back to the selected switch means.

6. In combination. electric circuit means for detecting external physical conditions including a plurality of pairs such conditions for controlling said circuit means, the switch means of each pair of which are connected in series relation to each other and the respective pairs of which are connected in parallel circuit relation to each other, means for testing said circuit means comprising a pair of electrically connected test switch means, common conductor means connecting points between the switch means of each of said plurality of pairs to each other and to a point between the switch means of said testing pair, a source of electromotive force, a plurality of electro responsive indicating means connected in parallel circuit relation to each other, and conducting means whereby, when a selected one of either of said test switch means is closed, a series circuit is established therefrom through said common conductor means, said parallel circuits, and back to the selected switch means, closure of both switches of the pair, of electrically connected switch means operating to close the said parallel circuit to energize said indicating means.

7. In combination, an electro responsive conand to any of the condition of said responsive means.

HARRY C. GRANT, JR. ARTHUR W. UHL.

REFERENCES CITED The following references are of file of this patent:

UNITED STATES PATENTS record in the of switch means responsive to 

